There has been a significant development within the technical field of crankcase gas cleaning. Increasingly tough environmental legislation has pushed the development of extremely efficient separators for removing particulate contaminants in the form of oil mist and soot particles from crankcase gas. At present, the most efficient crankcase gas separator comprises a centrifugal rotor having a stack of separation discs for separating the contaminants from the crankcase gas.
There are several ways of driving this centrifugal rotor. In a separator on the market today—the Alfdex® separator of the applicant—the centrifugal rotor may be driven either hydraulically or electrically.
The hydraulic drive comprises an oil turbine connected to the centrifugal rotor. A portion of the lubricating oil circulating in a combustion engine is conducted to a nozzle that directs an oil jet to drive the turbine of the centrifugal rotor. The advantage of this oil or hydraulically driven separator is that there already is an excess of oil flow available from the engine's lubrication pump. This is more than sufficient to drive the centrifugal rotor. Furthermore, the oil jet generates an oil mist through which the bearings of the centrifugal rotor are properly lubricated throughout the separator's service life. Last but not least, the hydraulic drive is both reliable and cost-efficient.
The other version of the Alfdex® separator comprises an electric drive with a brushless electric motor having a direct drive mechanism connecting the centrifugal rotor to the electric motor. This electric drive provides significantly lower energy consumption with cleaning efficiency adapted to the actual need. Accordingly, this version of the separator makes it possible to control the speed of the centrifugal rotor in an “efficiency-on-demand” operation. This technology is further described in documents EP 1537301 B1 and EP 1532352 B1.
The electric drive has great control capabilities and requires less intervention in the combustion engine, which simplifies installation. However, it involves a relatively high initial cost compared to the hydraulic version.